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GEOGRAPHY 20 – INTRODUCTION TO GIS EXAM 3 STUDY GUIDE VICKI DRAKE EARTH SCIENCE DEPARTMENT SANTA MONICA COLLEGE Data Management What is a Spatial Database? Can a database be used by two different Organizations for different purposes? Two approaches to Database Management: File Processing and Database Management – Similarities? Differences? Operations? Advantages and Disadvantages? Database Elements: Entity, object, attribute, attribute value, feature, Spatial object type, spatial primitives, symbol, database models, Layers (themes, coverages) o-dimensional object type 1-dimensional object type 2-dimensional object type Database Models: Hierarchical, Network, Relational – Advantages and Disadvantages of each type – Which one is used most often in a GIS? (Be able to define, describe, compare and contrast each of these Database Models – see Chapter 6 in Aronoff’s book) Database Structure – Tables, Queries, Tuples (Record row), Records,, Fields, Key Fields (Primary Key), (Digital Cartographic Data Standards Task Force terminology) “Data” vs. “Information” – Information systems function Geographic Data structures: Descriptive element – Graphical Element Four components of information systems – traditionally Main component driving Information systems today Data item (attribute), data file (flat file – hierarchical file), character Strings, numeric strings, Four perspectives of Information Systems: 1. Data Perspective, (Descriptive or Graphical Elements using either Raster Data method or Vector data method) Object view – Field View 2. Relationship Perspective – categorical relationships or spatial Relationships (Categorical): Classification system Nominal, Ordinal, Interval Ratio) Spatial: Topological, Proximal 3. Operating System Perspective (OS) Directories – subdirectories - GIS “Workspace” concept 4. Application Architecture Perspective Client/Server concept and implementation Descriptive Data Structure Object-Oriented Data Structure Type Constructor Graphic Data Structures (Raster/Vector) Raster Data Structure How represented? What is tessellation? Why use Raster format?? What is a TIN? What is a Quadtree? What is a run-length encoding compression? How is a Raster created? What are Raster data values? How is raster data stored? © Vicki Drake SMC – F-2000 1 Vector Data Structure How represented? Why use? How create? What is topology and how does it relate to Vector? What is “Adjacency” , “Connectivity”, “Containment” in terms of topology? How is Vector data stored? What is the Spaghetti Model of Vector Data? What is the Hierarchical Model of Vector Data? What is the Topological Model of Vector Data? Which one is more useful in a GIS? How is Vector data stored in each of these models? What is a Georelational Data Structure in Vector Data model? What are the Advantages or Disadvantages of using either a Raster Data Model or a Vector Data Model? GIS Analysis Functions Questions – functions – answers Basic spatial analysis: sorting, arithmetic, Boolean, statistical Logic Operations General Arithmetic Functions Rubber sheeting, data layers, rectification vs. registration, sliver, undershoot, overshoot, slope, aspect, buffer zones, Classification and reclassification processes Integrated processes Organization of Geographic Information within a GIS Four major groups of GIS analysis functions: Maintenance and Analysis of Spatial data (format, geometric, and map project transformations; conflation, edgematching, graphic element editing, line coordinate thinning) Maintenance and Analysis of Attribute Data Attribute editing functions, attribute query functions, Integrated Analysis of Spatial and Attribute Data Retrieval, classification and measurement functions, Overlay Operations (see notes), clipping, merging of polygons, ‘neighborhood operations’, topographic functions, Output formatting (reports, maps, etc.) What are the Boolean operations possible using Vector Data? What is reclassify, dissolve, and merge in relation to Vector Data operations and polygon overlays? What are sliver or spurious polygons in Vector data operations? © Vicki Drake SMC – F-2000 2